From the link
"If BIONICLE characters do eat (as I think they do), they do it by directly absorbing energy, not by chewing and swallowing as we do (except in very rare cases). They need energy because they are partially organic, but we do not know whether organic protodermis requires any kind of a circulatory system to function. There is no digestive system as we have, there is no waste. So they wouldn't need a circulatory system for that."
"Skakdi are known to chew and ingest their food, choosing to do so over the typical method of absorbing energy, as other inhabitants of the Matoran Universe view this act as repulsive."
Edit: seriously tho, LJ answered the question, not me